In the prior art, fluid systems are provided in which a high pressure stream of water, i.e., at pressures of 6,000 to 10,000 pounds or more, are used for many cleaning applications. In some of these systems one or more hand-held valve assemblies or guns are provided, and are connected by a hose to a common outlet of a pump. The guns generally include a housing having a valve therein, a barrel extension for directing the high pressure stream or water through a nozzle to the object to be cleaned, a handle or trigger mechanism for operating the valve, and a relatively unrestricted pressure relief or "dump" outlet for relieving pressure in the assembly when flow through the high pressure nozzle outlet is interrupted by operation of the valve.
In some applications it is desired to have a vertically suspended mechanism. Theses contain a stationary, hollow housing defining an enlarged opening in the top end for receiving a sealing structure for connection to a source of high pressure fluid, such as water, which may contain cleaning agents. A hollow spindle is journaled in the lower portion of the hollow housing and provides an axial passage for the high pressure fluid. A head secured to the lower end of the rotatable spindle defined fluid passages leading to one or more outlets in the form of nozzles which provide a high pressure generally downwardly directed spray for cleaning a surface or object. In order to avoid spot treatment and promote uniformity the outlet nozzles are generally slightly angled off the vertical axis of the device which, through reaction forces, creates a turning moment which causes the rotatable element to rotate in response to the reaction forces generated when the fluid is flowing.
A problem is encountered because on the one hand it is desirable to have minimum friction operating on the rotatable spindle so as to assure steady rotation of the hollow spindle in order to maintain the spray in a generally downward direction without excessive angulation off the vertical, and yet provide sufficient friction so that the rotatable element does not overspeed and turn at excessive speeds which will rapidly destroy the bearings. The reaction forces are difficult to estimate and it is difficult to balance the combination of frictional forces and reaction forces so that the rotatable portion of the housing containing the nozzles will steadily rotate but will not reach an excessively high speed.
It was discovered that the incorporation of a specially constructed magnetic rotor assembly on the rotatable spindle prevents the rotating mechanism from accelerating to an undesirably high speed but does not otherwise affect the operation. The magnetic rotor assembly includes permanent magnets which do not require the use of a battery.
Further experimentation with the aforementioned magnetic rotor assembly on the rotatable spindle reveals the fact that the magnetic rotor assembly would, at very high speeds, develop excessive heat due to the eddy currents created by the rotating magnets. Such localized heat can create distortion of the housing or spindle which can result in deterioration of the bearings of the apparatus and demagnetize the magnetic elements.